Update on contraindications in laser corneal refractive surgery

More than 25 years of experience with refractive surgery techniques (since the FDA [Food and Drug Administration] of the United States approved the use of the excimer laser in the remodeling of the cornea in 1995), added to the technological advances in ophthalmology (femtosecond laser, topography-guided ablation, anterior segment imaging systems) and increased understanding of refractive errors, higher order aberrations, and corneal biomechanics make corneal laser refractive surgery a safe method and effective for the correction of these defects. However, to date, there are still certain circumstances that represent a contraindication for its application, in addition to others that could be associated with complications, and that must be carefully analyzed. This review analyzes the current contraindications for laser corneal refractive surgery listed in the Preferred Practice Protocols (PPPs) of the American Academy of Ophthalmology and the Spanish Ophthalmology Society. These protocols are based on the best scientific evidence currently available and allow clear recommendations to be drawn, improving the safety profile of these techniques. Contraindications can be differentiated into relative or absolute; among the latter are: age less than 18 years, the absence of refractive stability and the existence of certain ocular pathologies (including certain corneal dystrophies, keratoconus, poorly controlled dry eye) or systemic pathologies (active autoimmune processes or poorly controlled diabetes mellitus). Other circumstances such as the use of certain drugs (amiodarone, isotretinoin), extreme values of mean central keratometry and pachymetry, history of previous uveitis or glaucoma, pregnancy and lactation, are considered relative contraindications according to the PPPs. However, there are studies that demonstrate the safety of refractive surgery in some of these cases.